Television screen



Feb.n 14, 1939. A

Filed Jan. 9, 1937 fwwl/L/ ATTORNEY NNNNNN O R5 FRITZ SCHROTER MAX KNOLLBY7 @Q10 BARTELSl F. scHRTER ETAL 2,146,994

Patented Feb. 14, 1939 UNITED! STATES PLA-TENT" oFFl-e TELEVISION SCREENApplicationl January 9, 1937; Serial# No. 119,715 InA Germany December23, 1935 6 Claims.

This invention relates broadlyV toA television scanning apparatus, andmore particularly to a grid screen of the type used in cathode rayvimagescannersy of the formA wherein the electronic charge imageis formedf onone side of the grid screen and the cathode" ray scanning deviceoperates and impinges on the other side of the grid screen. Such screenshave, in the prior art, been termed double side grid screens and broadlyare Well known.

It has been usual in the prior art to form the screen of a metallicsupporting structure which is multi-apertured, that is to say, is formedin a net or sieve-like form. Through each of the f apertures, aconducting element is passed, and on one extremity of the conductingelement is deposited a photoelectric material, and the other extremityis subject to the electron bombardment from the cathode ray. It is,therefore, obvious that these conducting elements must be insulated bothfrom each other and from the net or sievelike metallic body which actsas the supporting structure.

Heretofore it has been diicult in the manufacture of these screens toprovide adequate insulating means between the conducting elementshereinbefore referred to, which carry a photoelectric deposit, in such amanner that the screens could be made practicable from a commercialstandpoint.

It is, therefore, one of the objects of this invention to provide a gridscreen of such a nature as to be comparatively easy to manufacture and ascreen which will have adequate and desirable insulating means forelectrically separating the conducting elements passing through theapertures therein.

Our invention will be best understood by reference to the figure whichillustrates one embodiment.

Referring to the figure, the metallic supporting structure I0 mayconsist of a material Whose oxide is an electric insulator as, forinstance, tungsten, molybdenum, aluminum or tantalum. The aluminum isespecially desirable since its oxide has a high resistance not only tomechanical stresses which may take place when the conducting elementsare inserted, but due to the fact that its oxide forms a very goodinsulator. For forming the oxide on aluminum, it is usually preferableto produce the insulating layer by means of electrolytic oxidation.Tantalum possesses the advantage that its oxide when formed in a layeror by oxidation,has a very high (Cl. Z-27.5)

ohmic resistance' and itsadhesion to the metal itself is very great.

Adhering to the` metallic support Ill isV a layer of the oxide ofthemetaliwhich is used, the said oxide being formed in Well knownmanners as, for instance, by. electrolytic oxidation or directoxidation. The oxide layer II will then cover the outer surface of themetal I0 and will line the apertures I2 through which the conductingelements I3 pass. The conducting element I3 may in general be in theform of a pin, one of whose ends is formed of a frustro-conical section,and on the outer face of this section is deposited a layer ofphotoelectric material I4. 'Ihe pin then passes through the aperture andon its opposite side is subject to electronic bombardment on the surfaceI5.

For the purposes of clarity, there has been illustrated only one sectionof the screen greatly enlarged. It will be appreciated that theseconducting pins are sufficiently great in number so that the outersurface of the frustro-conical section which holds the photoelectricmaterial will be sufliciently close to that of the next pin so as toform a close fitting photoelectric mosaic.

It is possible also to provide the insulating surface on the sieve ornet-shaped metal body by chemical or electrolytic methods using a metalother than the supporting sieve whose oxide is an insulator as, forinstance, barium, caesium or magnesium. These substances may beevaporated in a vacuum and deposited on the metal netshaped support, andby subsequent oxidation, a successful and desirable insulating layer isformed.

What We claim is:

l. A cathode ray tube screen comprising a multi-apertured planarmetallic supporting structure, a uniform layer of the oxide of saidmetal formed integral with said metallic support in the aperturestherein, a plurality of conducting members each held in one of theapertures of the support structure, said members being of largercross-sectional area at one end thereof than the other end thereof, anda deposit of photoelectric material on the enlarged areas of each ofsaid members.

2. A cathode ray tube screen comprising a multi-apertured planartungsten supporting structure, a uniform vlayer of tungsten oxide formedintegral with said support, a plurality of conducting members each heldin one of the apertures of said supporting structure, said members beingof a pin formation and having one end thereof of greater cross-sectionalarea than the other end thereof, and a deposit of photoelectric materialon the enlarged areas of each of said members.

3. A cathode ray tube screen comprising a multi-apertured aluminumsupporting structure, a uniform layer o'f planar aluminum oxide formedintegral with said support, a plurality of conducting members each heldin one of the apertures of said supporting structure, said members beingof a pin formation and having one end thereof of greater cross-sectionalarea than the other end thereof, and a deposit of photoelectric materialon the enlarged areasl of each of said members.

4. A cathode ray tube screen comprising a multi-apertured molybdenumsupporting structure, a layer of uniform planar molybdenum oxide formedintegral with said support, a plurality of conducting members each heldin one of the apertures of said supporting structure, said members beingof a pin formation and having one end thereof of greater cross-sectionalarea than the other end thereof, and a deposit of photoelectric materialon the enlarged areas of each of said members.

5. A cathode ray tube screen comprising a multi-apertured metallicsupporting structure, a uniform layer of a planar metallic oxide formedintegral With said metallic support and in the apertures therein, aplurality of conducting members each held in one of the apertures of thesupporting structure, said members being of a pin formation and havingone end thereof of greater cross-sectional area than the other endthereof, and a deposit of photoelectric material on the enlarged areasof each of said members.

6. The method of forming a double mosaic screen structure whichcomprises the steps of producing a planar metallic electrode,perforating said electrode with a plurality of minute apere turestherein according to a predetermined regular pattern, oxidizing thesurface of the electrode includingthe apertured areas therein to provide

